Abstract: Radial velocity measurements of intracluster planetary nebulae (IPNe) have the potential to revolutionize our understanding of galaxy clusters. Ultra-low surface brightness images, such as that taken by Mihos \etal (2005) demonstrate the complexity of the intracluster stellar distribution, but by examining the distribution of IPNe in phase space, we can probe the physics of tidal stripping, the dark matter around galaxies, and the initial conditions of cluster formation. A recent example of the value of IPN measurements is presented by Doherty \etal (2009), who have used a very small sample of IPN velocities to argue that M87's stellar halo abruptly truncates at a galactocentric distance of ~ 150 kpc, and beyond this region, the potential of the cluster dominates. The recent improvements to the bench spectrograph of the WIYN+Hydra system now place large numbers of Virgo IPNe within reach. We propose to use this instrument to obtain the radial velocities of between 100 and 150 IPNe spanning the region from M87 to the Virgo Cluster ``core''. These measurements will triple the number of stellar radial velocities known in the cluster, and allow us to probe the origins of the intracluster stars and the process of hierarchical assembly.